1. Field of the Invention
The present invention relates to an electrostatic drive and a method for operating an electrostatic drive.
2. Description of Related Art
Micromechanical components such as micromechanical torsional actuators or translational microactuators, for example, frequently have an electrostatic drive whose electrodes are designed as multilayer electrodes. An electrostatic drive having at least two multilayer electrodes is often referred to as a multilayer comb drive.
FIGS. 1A and 1B show cross sections for illustrating a design and a mode of operation of a conventional electrostatic drive having multilayer electrodes.
The conventional electrostatic drive has a stator electrode 10 and an actuator electrode 12. The two electrodes 10 and 12 are designed as multilayer electrodes. A first separating layer 10a subdivides stator electrode 10 into two stator electrode subunits 10b and 10c which are electrically insulated from one another. Similarly, actuator electrode 12 is subdivided by a second separating layer 12a into two actuator electrode subunits 12b and 12c which are electrically insulated from one another.
If no voltage which is not equal to zero is applied between stator electrode subunits 10b and 10c and between actuator electrode subunits 12b and 12c, the two separating layers 10a and 12a are situated on a separating plane 14. First stator electrode subunit 10b and first actuator electrode subunit 12b are situated in a first deflection direction 16 of actuator electrode 12 in relation to separating plane 14. Similarly, second stator electrode subunit 10c and second actuator electrode subunit 12c are situated in a second deflection direction 18 of actuator electrode 12 in relation to separating plane 14.
As illustrated in FIG. 1A, applying a first potential P1 to first stator electrode subunit 10b and applying a second potential P2 which is not equal to first potential P1 to second actuator electrode subunit 12c results in a magnetic force between first stator electrode subunit 10b and second actuator electrode subunit 12c, and therefore in a deflection of actuator electrode 12 from its (non-energized) starting position into first deflection direction 16. Similarly, applying a third potential P3 to second stator electrode subunit 10c and applying a fourth potential P4, which is different from third potential P3, to first actuator electrode subunit 12b causes actuator electrode 12 to be displaced from its starting position into second deflection direction 18 (see FIG. 1B).
The illustrated electrostatic drive thus has the advantage that actuator electrode 12 may be moved from its non-energized starting position into two different deflection directions 16 and 18. Second deflection direction 18 is preferably oppositely directed with respect to first deflection direction 16.
The activation method in FIGS. 1A and 1B is known from the related art as the switching electrode actuator (SEA) method. Arbitrary, independent electrical potentials P1 through P4 are applied to various electrode subunits 10b, 10c, 12b, and 12c. With the aid of the electrostatic drive it is thus possible to selectively generate a force in deflection direction 16 or in deflection direction 18.
However, in the activation method in FIG. 1A no defined potential is present at electrode subunits 10c and 12b, which are not actively activated. Similarly, in the activation method in FIG. 1B, electrode subunits 10b and 12c which are not actively activated do not have a defined potential. For this reason, electrode subunits 10c and 12b (FIG. 1A) or 10b and 12c (FIG. 1B) which are not actively activated are also frequently referred to as floating electrode subunits 10c and 12b or 10b and 12c. 
However, for a change in direction of actuator electrode 12 which has previously been deflected in first deflection direction 16, a potential which is not equal to zero must be applied to electrode subunits 10c and 12b, which previously have not been actively activated. Thus, an electrical separation between a voltage source (not illustrated) for applying the potential which is not equal to zero and each of electrode subunits 10b, 10c, 12b, and 12c is usually necessary. However, such electrical separation, for example a high-impedance switch, is difficult to implement according to the related art.